It takes power to keep a job site humming. But when it comes to electricity, that power isn’t always where you need it. That’s where extension cords come to the rescue. The right cord will put you in business. The wrong one could shut you down.

Think of power cords as being hoses for electricity. You don’t want to put out a forest fire with a garden hose, but if you train one of those big boys the firefighters use on a flowerbed, the petunias will end up in a neighbor’s yard and you might blow away enough soil to reach bedrock. As with so many other things, size matters.

You don’t have to be an electrician to pick the right extension cord, but you do need to do some basic math. Power is measured either in amps (comparable to water pressure in a hose), or watts (the amount of water coming out). Cords are usually marked with the amps they will safely carry, but your tool power may be listed in watts—or even horsepower. To get from one to another, here are some basic formulas:

So a 5hp saw like the CC3500 Electric Self Propelled Concrete Saw has 3,750 watts of power (5 x 750), and if it’s running on 240 volts it will pull just under 16 amps (3750/240). A 2800-watt 16" hand-held TP 400 Cardi Electric Saw will pull about 23 amps at 120 volts.

The National Electrical Code (NEC) has several rules for using extension cords including where and how they should be used. It also sets limits on the amount of current that cords are permitted to carry to prevent overheating the cord. The limits for common wire gauges are listed below:

Just like a hose, a cord will also lose output based on friction, so the cord’s length becomes a factor, too. Prefab cords will have a load capacity stamped on them that takes the cord length into account.

At Ace Cutting Equipment, our people know how to match our selection of electric concrete saws with the extension cord that’s right for your power needs. We have over 100 years’ combined work experience at your service to help in choosing the right tools for your job. Give us a call at (888) 283-2597 or email steve@acecutting.com and we will gladly help with any questions you may have.